You may not have heard of tire crumbs—playground material made of ground up recycled tires–but it is the resilient, weatherproof, and low-maintenance material of choice for many playgrounds (including the Obama’s new playground at the White House. Could it also be toxic? The Environmental Protection Agency (EPA) is investigating after their own scientists raised concerns about its (and artificial grasses used on sports fields) possibly leaching toxic materials including neurotoxic chemicals like lead, and carcinogenic chemicals such as benzene. New York State has said that their new fields will no longer be made with tire crumbs. Until more is known the EPA has chosen to take a neutral stance on tire crumbs and artificial grasses. Previously the EPA recommended the products because they were recycled and therefore a step up for the environment.